TETANUS. 281 The pathology of the disease is of much interest be- cause of its purely toxic nature. There Is generally a small wound with a slight amount of suppuration. At the autopsy the organs of the body are normal in appear- ance, except the nervous system, which bears the great- est insult. It, however, shows little else than congestion either macroscopically or microscopically. An interesting fact contributed to our knowledge of the disease has bee^i presented by Vaillard and Rouget, who found that if the tetanus bacilli were introduced into the body freed from their poison, they were unable to produce any signs of disease because of the prompt- ness with which the phagocytes took them up. If, how- ever, their poison was not removed, or if the body-cells were injured by the simultaneous introduction of lactic acid or other chemical agents, the bacilli would imme- diately begin to manufacture the toxin and produce symptoms of the disease. The toxin is easily prepared, being readily soluble in water. The most ready method of preparation is to grow the bacilli in bouillon, keeping the culture-medium at a temperature of 37° C., and allowing it to remain un- disturbed for from two to four weeks, by which time it will have attained a toxicity so great that 0.000005 c.cm. will cause the death of a mouse. The toxin is very rapidly destroyed by heat, and cannot bear any temperature above 6o°-65° C. It is also decomposed by light. The best method of keeping it is to add 0.5 per cent, of phenol, and then store it in a cool, dark place. It will not keep its strength very long under the best conditions. The purified toxin of Brieger and Cohn was surely fatal to mice in doses of 0.00000005 gram. Lambert,1 in his comprehensive review of the use of tetanus antitoxin, points out that this is the most poisonous substance that has ever been discovered. By the gradual introduction of such a toxin into ani- mals Behring and Kitasato have been able to produce in 1 New York Med. your., June 5, 1897.